Your truck can have 2 or 4 wheel ABS. Below are 2 links for both wire diagrams.
We need to unplug the rear axle speed sensor and the GEM module or the ABS module. OHM test both speed sensor wires from both ends to see if the wires are broken. Then OHM test them together to see if they are shorted to each other. Then from either end OHM test both wires to both battery posts to see if the wires are shorted to anything else. Your readings for each test should be 0.0, 0.0, OL out of limits, OL, and OL. If this is what you get then the wiring to the sensor is fine.The sensor is new, so its fine.
That means its either module depending on the setup you have or the wire from the module to the PCM and instrument cluster. So next you need to OHM test that wire to only see if its broken. If its fine then its the module to blame, for not making a VSS signal.
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